A pure-foil PET / AL / LDPE sheet-mask pouch holds oxygen and water-vapour transmission at ≤0.1 cc (or g) per m² per 24 h and blocks light completely; it costs about 30% more per unit than a metallised pouch. A clear PET / PE laminate shows the product but passes light and oxygen at roughly 150–300 units for PE — unsuitable for serums with vitamin C, retinol or botanical actives. The foil-free middle is PET / EVOH / PE, passing oxygen at about 0.2 units versus 150–300 for single-layer PE, and metallised PET / VMPET / PE at a good but pinhole-sensitive barrier. MOQ is set by the gravure cylinders, not the film — ~30,000 at smaller converters, ~100,000 at large ones — and every structure is signed against top seal ≥60 N/15 mm, side seals ≥65 N/15 mm.
The structures, layer by layer
A sheet-mask pouch is a laminate: a printable outer film, a barrier layer, and a heat-sealable inner film that touches the serum. Which barrier layer you choose — aluminium foil, metallised film, EVOH or none — is the whole decision.
| Structure | Oxygen / moisture barrier | Light | Recycle status | Cost position | Use it for |
|---|---|---|---|---|---|
| PET / AL / LDPE (pure aluminium foil) | OTR ≤0.1 cc/m²·24 h; WVTR ≤0.1 g/m²·24 h (GB/T 1038 / 1037) — the mask-pouch standard | Opaque | Multi-material; not kerbside-recyclable | About 30% higher unit price than metallised | Sheet masks, serums, anything light- or oxygen-sensitive |
| PET / VMPET / PE (metallised) | Good, below foil; pinholes matter | Opaque to near-opaque | Multi-material | Baseline foil-look pouch | Samples, wipes, powders; masks with robust formulas |
| PET / EVOH / PE (foil-free barrier) | High: EVOH passes oxygen at roughly 0.2 units versus 150–300 for single-layer PE | Transparent unless printed | Foil-free, metal-detectable | Mid | Oil- or fragrance-led formulas that want a foil-free look; clear window with a barrier |
| PET / PE (clear, no barrier layer) | Light: OTR in the 150–300 range for PE | Transparent | Multi-material; mono-PE variants recycle-ready where accepted | Baseline | Wash-off products, dry sheets, short shelf life |
| Mono-PE or mono-PP laminate | Light: OTR 150–300 for PE | Transparent or printed | Recycle-ready where the market stream accepts it | Baseline | Refill spout pouches, doypacks for wash-off products |
Two-, three- and four-layer variants exist for a reason. Handbook practice for mask pouches lists two-layer OPP/VMPET or PET/PE, three-layer matte-OPP / VMPET / PE or OPP / VMPET / PE as the common mask structure, and a four-layer PET / NY / VMPET / PE where a nylon layer is added for softness and tear toughness. The face film decides the finish — a matte OPP or matte PET top gives the soft-matte look; gloss PET the mirror look — and it is specified at the structure stage, not as a finish afterwards.
Barrier: the number that decides it
A sheet-mask serum is water-based, often with actives, and sits in the pouch for up to two years. Three things degrade it: oxygen, water loss and light. Aluminium foil stops all three — the standard pass mark is OTR ≤0.1 cc/m²·24 h and WVTR ≤0.1 g/m²·24 h, and foil is opaque. That is why foil is the mask-pouch default and why the compatibility matrix gives a hard rule: serum with vitamin C or retinol → foil, or PET / EVOH / PE.
A clear PET / PE laminate has no barrier layer. Single-layer PE passes oxygen in the 150–300 range, and the pouch is transparent, so the serum sees light on every shelf. It is fine for a wash-off clay sheet, a dry cellulose sheet the consumer wets, or a product with a short shelf life. It is not fine for an active serum, and no amount of print changes the barrier.
EVOH is the honest middle. A PET / EVOH / PE structure passes oxygen at roughly 0.2 units against 150–300 for plain PE — three orders of magnitude better — while staying foil-free and transparent where unprinted. If the design needs a window to show the mask, a barrier window film (EVOH-based) keeps the barrier; a plain PE window breaks it. Metallised VMPET sits between: a good barrier at about 30% less cost than foil, but vacuum-deposited aluminium has pinholes, so it is specified for robust formulas and samples rather than long-life actives.
MOQ: the same for foil and clear
This is the part that surprises. The minimum for a printed pouch is set by the rotogravure cylinders — RMB 850–1,500 (≈USD 120–210) per colour — and by the press speed, not by which film is on the web. So a foil pouch and a clear pouch with the same artwork carry the same floor: around 100,000 pieces per design at large converters, around 30,000 at smaller ones, in 15–20 days including plate making with ±10% over- or under-run. What changes is the unit price — foil about 30% above metallised — and, on a custom structure, the lead time: stock film with custom print is 25–35 days door to factory gate, a new structure or sealant 55–75 days. The ways under the floor — smaller converter, shared cylinders, roll film, label on a plain pouch from ~500 — are on the sheet mask pouch MOQ guide and the MOQ index.
Seal strength: the same pass marks for every structure
Barrier is useless if the seal fails, and the seal is where the structures differ in practice rather than in specification. Foil laminates seal through a PE sealant and are stiff, so seal jaws must be flat and clean; clear PE laminates seal easily but can thin at the seal if the temperature is high. The pass marks do not move:
| Test | Method / standard | Pass threshold — all structures |
|---|---|---|
| Heat-seal strength — top seal | QB/T 2358 peel | ≥60 N/15 mm |
| Heat-seal strength — side seals | QB/T 2358 peel | ≥65 N/15 mm |
| Tensile strength / elongation | GB/T 1040.3 | ≥50 N/15 mm; break force ≥50 N; elongation ≥77% |
| Interlayer peel (delamination) | GB/T 8808 | BOPP/AL ≥0.5 N/15 mm; AL/PE ≥2.5 N/15 mm |
| Compression | Filled to net content, 200 N for 10 min | No burst, no leak |
| Vacuum seal | Filled with water, −0.06 MPa for 1 min | No leakage |
| Barrier | GB/T 1037 (WVTR), GB/T 1038 (OTR) | ≤0.1 g/m²·24 h and ≤0.1 cc/m²·24 h on foil; agreed per structure otherwise |
| Solvent residue | GB/T 10004 | ≤10 mg/m² |
| Thickness | Micrometer, 0.001 mm | Total laminate within ±8% of the standard sample |
| Cold / heat / light | 30 ml of bulk sealed in; −10°C (or −18°C) 7 days; 50°C 7 days; light cabinet 7 days | No visible change against the control — the light leg is where clear pouches fail |
| Heat sterilisation (where used) | Retort | 121°C for no more than 40 min, or 135°C for no more than 30 min; water-bath cooling to 40°C under pressure |
| Microbiology (irradiated lots) | Plate count | ≤10 CFU/g total; ≤10 CFU/g yeast and mould; irradiation certificate per batch |
Two process notes from converter practice. Laminate defects — wrinkling, solvent residue, pinholing, bubbles — are the four things to inspect on the first roll. And cooling a heat-sterilised pouch in cold water shears the adhesive layer; it is cooled slowly in a water bath to 40°C under pressure. The gates are on the QC standards.
Which structure for which mask
- Serum with vitamin C, retinol, peptides or botanical actives, 2-year shelf life: PET / AL / LDPE foil. Matte or gloss face film chosen at the structure stage.
- Oil- or fragrance-led essence, foil-free positioning: PET / EVOH / PE, with the sealant and ink checked against essential oils in a 48°C / 30-day hold — oils extract plasticisers and lift ordinary inks.
- Want to show the mask: printed foil with a barrier window film, or PET / EVOH / PE — never a plain PE window on a foil pouch.
- Toner or mist above ~30% ethanol: foil laminate with a PE sealant, and test the sealant; never a PET contact layer.
- Wash-off clay sheet, dry sheet, short shelf life, samples: metallised PET / VMPET / PE or clear PET / PE at baseline cost.
- Recycle-ready claim: mono-PE where the market's stream accepts it — accepting the light barrier that comes with it.
Brief the structure by name, the barrier as a number, the face-film finish, the sealant and the tests above; then check the converter's answers against how to evaluate a China packaging supplier. The full structures and thresholds are on flexible packaging and pouches; masks and sachets for treatment lines sit in the skincare packaging solution.
Vella is a Guangzhou-based beauty packaging solutions provider — a sourcing partner, not a factory — that fixes the pouch structure, barrier number, sealant and face-film finish in the spec, routes the run to partner converters matched to the 30,000 or 100,000 floor, and signs the pouch against seal, barrier and the 7-day cold / heat / light legs with your actual serum before production. Partner factories operate to ISO 22716 / GMP; empty packaging only.
Common questions
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